Abstract
Consider a wireless sensor network (WSN) where a broadcast from a sensor node does not reach all sensor nodes in the network; such networks are often called multihop networks. Sensor nodes take individual sensor readings, however, in many cases, it is relevant to compute aggregated quantities of these readings. In fact, the minimum and maximum of all sensor readings at an instant are often interesting because they indicate abnormal behavior, for example if the maximum temperature is very high then it may be that a fire has broken out. In this context, we propose an algorithm for computing the min or max of sensor readings in a multihop network. This algorithm has the particularly interesting property of having a time complexity that does not depend on the number of sensor nodes; only the network diameter and the range of the value domain of sensor readings matter. © 2009 pringer Science+Business Media B.V.

Abstract
The options to implement a coherent optical system employing a phase estimation algorithm combined with adaptive linear equalization are investigated. Several carrier phase estimator strategies are discussed, in terms of parallelization, performance and implementation complexity.

Abstract
This chapter focuses on adding spatial and sensory information to mobile technologies to augment the affordability of mobile world exploration by primary school children. It starts by analyzing the significance of space and senses in children's literacy and mobile learning applications. The opportunities and constraints associated with the use of mobile technologies for the exploration of senses and space within primary school learning activities are explored. The experience of the SchoolSenses@Internet project that designed a mobile application for creating georeferenced multisensory messages within a classroom collaborative environmental activity is described, highlighting the goals, development, and implementation processes. A study carried out over an academic year to investigate how children use GPS-equipped mobile phones to explore, create, and share multisensory geographic information is presented and analyzed to evaluate the use of mobile technology in environmental education and to assess learning achievements. The design and implementation process of the application is outlined, and the lessons learned are identified and summarized in the chapter. © 2009 Elsevier Inc. All rights reserved.

Abstract
As formal verification tools gain popularity, the problem arises of making them more accessible to engineers. A correct understanding of the logics in which properties are expressed is needed in order to guarantee that properties correctly encode the intent of the verification process. Writing appropriate properties, in a logic suitable for verification, is a skilful process. Errors in this step of the process can create serious problems since a false sense of security if gained with the analysis. However, when compared to the effort put into developing and applying modelling languages, little attention has been devoted to the process of writing properties that accurately capture verification requirements. This paper illustrates how a collection of property patterns, and its tool support, can help in simplifying the process of generating logical formulae from informally expressed requirements. © 2009 IFAC.

Abstract
The electrical power production from dispersed energy sources or distributed generation is playing an increasing role in the supply of electricity in the liberalized electricity markets. Distributed generation can have a significant impact on the power flow, voltage profile, stability and the power quality for both customers and electricity suppliers. In this paper it is studied and analysed the influence of a wind farm in the dynamic voltage stability of a power network. A short-circuit in the middle of the transmission line and a significant load demand disturbance situation were simulated. The automatic voltage regulators of the generating units, the turbine speed governors and the double fed induction generator models were taken into account. The simulation results were obtained using the EUROSTAG software package. Finally, some conclusions that provide a better understanding of the dynamic voltage stability are pointed out.

Abstract
In this paper is presented a Game Theory based methodology to allocate transmission costs, considering cooperation and competition between producers. As original contribution, it finds the degree of participation on the additional costs according to the demand behavior. A comparative study was carried out between the obtained results using Nucleolus balance and Shapley Value, with other techniques such as Averages Allocation method and the Generalized Generation Distribution Factors method (GGDF). As example, a six nodes network was used for the simulations. The results demonstrate the ability to find adequate solutions on open access environment to the networks.